1. Field of the Invention
The present invention relates to apparatus and method for supplying photoresist, and more particularly, to a photoresist supply apparatus capable of controlling the flow length of photoresist, and a method of supplying photoresist using the same.
2. Description of the Related Art
Generally, a lithography process is performed during manufacture of integrated circuit (IC) semiconductor devices in order to form a pattern on a particular layer of a semiconductor wafer. The lithography process is performing exposure and development after photoresist is deposited on a semiconductor wafer. Accordingly, in order to deposit photoresist on a semiconductor wafer, a photoresist supply apparatus for supplying photoresist over the semiconductor wafer is required.
In the meantime, as the degree of integration of IC semiconductor devices increases, it is increasingly necessary to very precisely control the ejected amount and pressure of photoresist that is supplied on a semiconductor wafer. However, in conventional photoresist supply apparatuses, the amount and pressure of photoresist continuously ejected over a semiconductor wafer may not correct due to various causes such as changes in the pressure of a pump for supplying photoresist, i.e., a blocked-up photoresist filter and a change in the pressure of air supplied for turning on/off a valve.
When the amount and pressure of photoresist ejected over a semiconductor wafer incorrectly change, the flow length of photoresist remaining at a nozzle unit frequently changes. In addition, when exposure and development processes are performed under the state in which the photoresist flow length at the nozzle unit changes, particles occur in the surface of a semiconductor wafer after the exposure and development processes. In the worst cases, deposition of photoresist and an exposure process must be performed again, or the semiconductor wafer must be discarded.
To solve the above-described problems, it is a first object of the present invention to provide a photoresist supply apparatus capable of continuously and precisely controlling the interrupt of photoresist ejected over a semiconductor wafer by measuring the flow length of photoresist remaining at a nozzle unit.
It is a second object of the present invention to provide a method of supplying photoresist using the above photoresist supply apparatus.
To achieve the first object of the present invention, a photoresist supply apparatus includes a photoresist supply unit for supplying photoresist; an automatic on/off valve connected to the photoresist supply unit, for controlling the flow of photoresist supplied from the photoresist supply unit; and a nozzle unit connected to the automatic on/off valve, for ejecting photoresist over a wafer. The automatic on/off valve may be composed of a cut-off valve and a suckback valve.
In addition, the photoresist supply apparatus includes a photoresist flow length measurer for measuring the flow length of photoresist remaining at a tip of the nozzle unit after interrupt of ejection through the nozzle unit; a measured data processor for converting data measured by the photoresist flow length measurer into an electrical signal; and a valve controller for finely controlling the flow length of photoresist remaining at the nozzle unit in response to the electrical signal fed back from the measured data processor. The photoresist flow length measurer may be manifested as a camera. The data measured by the photoresist flow length measurer may be an image signal. The valve controller may be manifested as a speed controller which controls the amount of air flowing into the automatic on/off valve. The speed controller may be composed of a stepping motor and an air control unit, which is connected to the stepping motor and controls the amount of air discharging into the automatic on/off valve.
To achieve the second object of the present invention, a method of supplying photoresist includes supplying photoresist to a nozzle unit through an automatic on/off valve. After interrupting photoresist supply to the nozzle unit by turning off the automatic on/off valve, the flow length of photoresist remaining at a tip of the nozzle unit is measured. The flow length of photoresist may be measured using a camera. After converting the measured flow length of photoresist into an electrical signal, the electrical signal is fed back to the valve controller, and the flow length of photoresist is finely controlled based on the electrical signal. The valve controller can finely control the flow length of photoresist by controlling the amount of air flowing into the automatic on/off valve. The valve controller may be manifested as a speed controller.
The above-described present invention measures the flow length of photoresist remaining at the nozzle unit and continuously and precisely controls the flow length of photoresist remaining after being ejected over a semiconductor wafer, thereby maintaining the flow length of photoresist consistent.